Year	Percent
1990	5.32
1991	5.29
1992	5.26
1993	5.23
1994	5.2
1995	5.17
1996	5.14
1997	5.11
1998	5.08
1999	5.05
2000	5.02
2001	4.99
2002	4.97
2003	4.94
2004	4.91
2005	4.88
2006	4.78
2007	4.68
2008	4.58
2009	4.47
2010	4.37
2011	4.27
2012	4.17
2013	4.07
2014	3.97
2015	3.87